Inverter for an electronic ballast having independent start-up and operational output voltages
First Claim
1. An electronic ballast for energizing a gas-discharge lamp, the electronic ballast comprising:
- a square-wave amplifier having a square-wave amplifier input and a square-wave amplifier output;
a lamp control circuit including an oscillator;
the oscillator oscillating at any oscillator frequency within an entire oscillator frequency range during a start-up mode of the lamp, the lamp control circuit providing a signal at the oscillator frequency to the square-wave amplifier input;
a resonant circuit coupled to the square-wave amplifier output;
the resonant circuit having a resonant frequency, a relative frequency difference between the oscillator frequency and the resonant frequency determining the luminance of the lamp during an operational mode of the lamp;
a step-up transformer having a primary winding and a secondary winding;
the primary winding receiving electromagnetic energy from the square-wave amplifier output;
a ratio of primary winding turns to secondary winding turns selected to provide a transformer secondary voltage that equals or exceeds a start-up threshold voltage of the lamp, the ratio depending upon a transformer primary voltage.
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Accused Products
Abstract
The electronic ballast for a gas-discharge lamp includes an inverter. The inverter uses the combination of a step-up transformer, a resonant circuit, and clamping diodes to provide an operational inverter output voltage that is independent of the start-up output voltage of the inverter. During the start-up mode, the step-up transformer is used to provide the start-up voltage for the lamp and the resonant circuit is inactive. Clamping diodes prevent or inhibit the resonant circuit from resonating with potential parasitic capacitances during the start-up mode. During the operational mode, an oscillator is tuned relative to the resonant frequency of a resonant circuit to control the brightness of the fluorescent lamp.
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Citations
35 Claims
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1. An electronic ballast for energizing a gas-discharge lamp, the electronic ballast comprising:
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a square-wave amplifier having a square-wave amplifier input and a square-wave amplifier output; a lamp control circuit including an oscillator;
the oscillator oscillating at any oscillator frequency within an entire oscillator frequency range during a start-up mode of the lamp, the lamp control circuit providing a signal at the oscillator frequency to the square-wave amplifier input;a resonant circuit coupled to the square-wave amplifier output;
the resonant circuit having a resonant frequency, a relative frequency difference between the oscillator frequency and the resonant frequency determining the luminance of the lamp during an operational mode of the lamp;a step-up transformer having a primary winding and a secondary winding;
the primary winding receiving electromagnetic energy from the square-wave amplifier output;
a ratio of primary winding turns to secondary winding turns selected to provide a transformer secondary voltage that equals or exceeds a start-up threshold voltage of the lamp, the ratio depending upon a transformer primary voltage. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. An inverter for initially energizing a gas discharge lamp in a start-up mode and subsequently operating the gas-discharge lamp in an operational mode, the inverter comprising:
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a square-wave amplifier, the square-wave amplifier having a square-wave amplifier input and a square-wave amplifier output; a transformer having a primary winding and a secondary winding, a ratio of turns of the primary winding to the secondary winding selected to provide a sufficient threshold voltage on the secondary winding during the start-up mode to initially illuminate the lamp; a first resonant element connected to the primary winding and the square-wave amplifier output, a second resonant element connected to the secondary winding;
the second resonant element electrically floating during the start-up mode;
the first resonant element and the second resonant element only forming a series resonant circuit during the operational mode of the lamp;
the series resonant circuit having a resonant frequency;a lamp control circuit including an oscillator having an oscillator frequency, the oscillator frequency designated as a starting frequency during the start-up mode and an operational frequency during the operational mode;
the oscillator being associated with the square-wave amplifier;
the lamp control circuit determining a frequency separation between the operational frequency and the resonant frequency to adjust luminance of the lamp during the operational mode. - View Dependent Claims (20, 21, 22, 23, 24, 25, 26)
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27. A lighting system for energizing multiple gas-discharge lamps comprising:
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a central ballast unit, the central ballast unit including a converter and a main lamp control circuit;
the converter having a positive direct current output and a negative direct current output, the main lamp control circuit including a main oscillator operating at a main oscillator frequency, the main lamp control circuit having a control input and a main control output;a plurality of remote inverters, the remote inverters connected to the central ballast unit;
each remote inverter comprising a square-wave amplifier, a transformer, and a resonant circuit;the square-wave amplifier having a square-wave amplifier input and an square-wave amplifier output, the square-wave amplifier manipulating power from the positive direct current output and the negative direct current output; the transformer having a primary winding and a secondary winding, the ratio of turns on the primary winding to the secondary winding selected to provide a sufficient threshold voltage during a start-up mode to illuminate at least one lamp; and the resonant circuit coupled to the transformer and receiving the square-wave amplifier output, the resonant circuit having a resonant frequency in an operational mode following the start-up mode of the lamp. - View Dependent Claims (28, 29, 30, 31, 32, 33, 34, 35)
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Specification